<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .hello {
            width: 1000px;
            height: 200px;
            margin: 100px auto;
            background: red;
        }
        .sk {
            margin:20px 30px;
            /*设置padding与border*/
            padding:10px;
            border: 3px solid #000;
            background: yellow;
        }
    </style>
</head>
<body>
<div class="hello">
    <div class="sk">
        <div class="classs">
            111
        </div>
    </div>
</div>
</body>
</html>